Drop-on-demand and continuous jetting technologies have been used for many years to jet colorant onto various substrates for the purposes of printing documents, labels, digital photographs and the like. Inkjet printing technology is commonly used in many commercial products such as computer printers, graphics plotters, copiers, and facsimile machines. The small drops of fluid that can be achieved with inkjet technology make the technology desirable for other applications as well. Recently, there has been interest in using jetting technologies for the precision dispensing of high value materials. For example, inkjet technology could be used to dispense reagents, enzymes or other proteins into well-plates for the purpose of fluid mixing or initiating chemical reactions. Other examples of alternative applications include the printing of LCD color filters and transistor back-planes.
In a laboratory environment, it is useful to be able to accurately dispense small volumes of various fluids. Having a number of dispensers available with different dispensing geometries increases the likelihood of being able to achieve the desired drop volume or line width for a particular fluid. However, it is often unknown what drop volume will come out of a particular dispenser with a particular fluid (e.g., ethanol, water and toluene will all give different drop volumes from the same physical dispensing geometry). While it is possible to develop computational models (based on fluid-substrate interaction and drop volume size relative to fundamental fluid properties such as specific heat, heat of vaporization, boiling temperature, etc.) to predict drop volumes, the physics behind drop/substrate interaction and nucleation parameters for various fluids are complicated, and such models can be uncertain and fraught with errors. Accordingly, it is often easier and faster to determine the appropriate dispensing geometry empirically. This entails filling multiple dispensers with the particular fluid to determine which one provides the desired drop volume or line width. Filling multiple dispensers to empirically discover the proper geometry requires a relatively large amount of the fluid and is thus expensive when dealing with high-value fluids.